Short Knocking/rattling sound when accelerating..? 2015 Yukon Denali

[DiaNali]

I just bought a pre-owned 2015 Yukon Denali and I Love it! 

I've been waiting for the feel of a big V8 engine with 4 wheel drive so this girl can dirty on any road.. It's beautiful and I'm SO happy to own a sexy Denali.

  I've only had it for two weeks so I'm learning every thing about it with each drive. So far the engine purrs and all gauges read level. It's got 98k mi on it 

so I'm expecting it to have some wear and tear.  So just yesterday morning I pulled away from a stop sign and gave a good rev got up to 50mph in a few sec...

and as I approached a slow zone I took my foot off the gas.. lowered speed to about 25 then gave it a little more gas while going up a slight hill in the road and I hear what sounded like a knocking noise. I took my foot off the gas and the sound went away. So on the drive home where I have to ascend up to about 2200 ft elevation it did it again as I was coasting and had to accelerate from 25 to around 30 mph I kept my foot on the gas this time (engine sounding smooth as silk) and continued uphill about 45mph and the sound went away. It's always a short knocking/rattling sound. Not in the engine but below me, definitely upfront.

 I've got an appt at GMC next week but until then I'd love to figure it out. Not sure what other details you need but any one got any idea?

 

 

Thanks everyone! 

-Dia

[newdude]

What type of gas do you put in it?

 

6.2 needs 91 octane at a minimum.  87 octane can and will produce knocking and pinging.  

[DiaNali]

I only give it 91 or 93 Octane.

The sound is more a rattle not so much knocking or pinging from the drive shaft not in the engine.....

 

Maybe transfer case or fuel injectors?

I used to be a service writer at Chrysler and PDI for several years.

I can usually pinpoint the sound I am just not use to the "sounds" of my GMC yet.

 

It's currently at the dealership for service cant wait to hear what they find. 

Edited October 15, 2021 by DiaNali

[DiaNali]

OK FOUND OUT WHAT IT IS!

 

  A MISFIRE. APPARENTLY AS THIS DENALI CAN SWITCH BETWEEN V4 OR V8 ,

THE NOISE I WAS HEARING IS A MISFIRE WHEN IT'S TRYING TO SHIFT BETWEEN THE TWO.

SOMETHING COMMON ON THIS YEAR WITH 90K+ MILES.

 

SO MUCH FUN.  MY BEAUTIFUL DENALI I GOT TO DRIVE FOR LESS THAN 2 WEEKS WILL BE AT THE DEALERSHIP FOR A COUPLE OF WEEKS. BUT.. WHILE SHE'S THERE.. I'M HAVING EVERY SINGLE NOOK AND CRANNY LOOKED OVER AND BROUGHT UP TO PAR.  

 

JUST WANTED TO UPDATE YOU ALL ON WHAT THE ISSUE WAS WITH MY NALI 

 

 

 

[JimCost2014]

On 10/19/2021 at 7:16 PM, DiaNali said:

OK FOUND OUT WHAT IT IS!

 

  A MISFIRE. APPARENTLY AS THIS DENALI CAN SWITCH BETWEEN V4 OR V8 ,

THE NOISE I WAS HEARING IS A MISFIRE WHEN IT'S TRYING TO SHIFT BETWEEN THE TWO.

SOMETHING COMMON ON THIS YEAR WITH 90K+ MILES.

 

SO MUCH FUN.  MY BEAUTIFUL DENALI I GOT TO DRIVE FOR LESS THAN 2 WEEKS WILL BE AT THE DEALERSHIP FOR A COUPLE OF WEEKS. BUT.. WHILE SHE'S THERE.. I'M HAVING EVERY SINGLE NOOK AND CRANNY LOOKED OVER AND BROUGHT UP TO PAR.  

 

JUST WANTED TO UPDATE YOU ALL ON WHAT THE ISSUE WAS WITH MY NALI 

 

 

 

Welcome to the site.

 

Any further updates?